Methods and flame generating apparatus for spectrophotometric quantitative analysis



ec. 5, 1950 T. E. WEICHSELBAUM METHOD AND FLAME GENERATING APPARATUS FOR SFECTROFHOTOMETRIC QUANTITATIVE ANALYSIS Filed Oct. 21, 1948 INVENTOR THEODORE E. WEICHSELBAUM FIG. 3

ATTORNEY Patented Dec 5, 1950 uurr zo- STATES. PATENT OFFICE METHODS, ND FLAME GENERATING AP- ARATUS FOR- SPECTBOPHOTOMETRIC QUANTITATIVE ANALYSIS A Theodore 'E. Weichselbaum, Normandy, Mo., as- .signor to Applied Research'Corporation, a corporation of Missouri Application was, 31;; 1948, Serial No. 55.754

. nomine- This l lon relates in s neral to marital and apparatusfor spectro photom etricquantita tiveanalysis and, more particularlm to a ,new

and novel flame injection burner-for use-inton junction with'spectro-photonieters.

At the present time; extensive efiorts have been made to perform quantitative analyses upon solutions containing heat-ionizable cations by photo; metricjmethods-by introducing a measured quan tity of such solution into an orgy-hydrogen, 'oxyg V gen gas or gas-air flame and determininglby spectre-photometric means, the intensity of color thereby imparted t0 the flame. fAppreciable inaccuracies and inconclusive results have i been. j encountered and difliculties in' i'educ'ing -such 1 v methods to. reliable routines have resulted due to lack .offprecision in the methods-and apparatus y which the solution being analyzed is; introduced. to the flame.

are simple; accurate and precise.

It is a'furthei object of to provide for use with aphotometerasimple,

the present invention.

characters wall-5, a back wall sub-dividing the V ment ;c.' I

,-compartmentb is a-switch-back multivoltmeter in .the'r usefof a color-analyzing photometer in 'combination withan oxy-hydrogen or oxygengas burner ors'o-c'alled lamp having means forv introducing'a"precisely constant flow of the-liquid or solution to be analyzeddirectly into the interior portion of the flame.

Referring nowin more detail and by reference to 'the drawing,- which-illustrates a preferred embodiment of the present invention,

A designates a photometric quantitative analysis apparatus comprising a cabinet I having a bottom wall 2,.'a front wall 3, sidewalls 4, a top 6, and a. vertical partition I cabinet transverselyinto-an instrument compartment b' and aburner compart- Suitably mounted in the instrument comprising a potentiometric indicator 8, "galva- It is, hence, the primaryobject of the present inventionto provide methods and apparatu'sior-f; spectre-photometric quantitative analysis which nometer 9, and variable-resistance control knobs IO, N, conventionally connected in circuit with each other and with one or more photocells or photo-tubes l2, in such a manner that the voltage in-thecircuih as shown in the galvanometer 9,

highly eflicient flame. producing apparatus orburner which is capable of accuratre, reliable and 3 uniform operation. 1' y f It is also an object of the present invention to provide a photometric burner having injection.

means capable of introducing a solution to be analyzed into'the flame at a steady uniform rate and in an accurately, controlled amountso as to produce a photometrically measurable flame-efmay be controlledby the knobs I0, I I, to balance thev'oltage' output of the photocells l2 as shown on the indicator 8. The photometric circuit, in

- itself. m ay be of any well known type and hence has not beenillustrated.

The'photocell I2 is located adjacent the partition 'I- opposite a window or aperture l3 therein and interposed between the photocell l2 and a feet whichbea'rs a precise quantitative relation to the chemical constituency of such solution.

It is an additional object of the invention to provide apparatusof the type stated which. is economical in construction'and simple in operation.- f

In the drawing, 4

' Figure 1 is a front elevational view of photo window H are a lens l4 and color filter l5, as schematically indicated in Figure 1 and for purposes presently rnore fully appearing.

The portion of the front wall 3 extending across the burner compartment-ac is provided witha'large rectangular opening [6 and welded or otherwise fixed upon the bottom wall 2 inmetric quantitative'analyticalapparatus constructed in accordance with and embodying the f present invention.-

Figure 2 is a fragmental vertical sectional view,

paratus taken along line, 2-2 of Figure l. I

Figures 3 and 4 are fragmentary vertical sectional view taken along lines 3-.3 and 4-4 re-- spectively of Figure 2; and

Figure 5 is a top plan view ofthe burner forming a part of the present invention.

Broadly speaking-the present invention resides .of the photometric quantitative analytical api I Iwardly of and substantially centered, with respect to, the opening l6, are longitudinally spaced pairsoflaterally aligned pivot-lugs l'I. Swingably mounted at their lower ends upon the pivotlugs Il arep-airsof parallel links l9, respectively, which are, in turn, 'swingably connected at their I upper ends to depending ears 20 formed integrally with a tray-bar 21 extending at its forward. end outwardly through the opening IS in the formation of a handle 22 and being provided adjacent its interior end with a tray 23 adapted to receive and retain a sample-holding beaker 24.

J ournaled in and extending horizontally between the front wall 3 and back wall 6', preferably midway between the pivot-lugs 'I1. is a shaft 25- provided on its outer end with a knurled operating knob 26 and on its inner end with a locking blade 21 having a flat transverse end face 28 for op tional engagement with the interior end. of the tray-bar 2|, as shown in Figures 2 and 4. It should be noted ,in this connection that the links l9 are of s'uchlength, with respect to each other, and are so arranged that the tray-bar 2| will always remain horizontal as it is shifted .up and the capillary 56 is so positioned in relation to the arc of movement of the beaker 24, as it moves from upper to lower position, that it will clear the dge of the beaker 24 and will be located close to the bottom of the beaker 24 when the latter is in elevated position. The ,upper'end of' the capillary 56 extends through and is of substantially smaller diameter than the bore 44 of down and the locking blade 21 is of such width I that when inupright positionfasshown in full lines in Figure 4, the tray-bar 2| will rest-on the flat end face 28 and he supported stationarlly in upwardlyshifted-position, On theother hand, when the lock ng blade 21 is swung down to the horizontal position, shown in dotted lines in Figure 4, the tray-bar 2| may be manually lowered to the position shown in dotted lines'in Fi ure 2.

Supported, by means of abracket 29, within the burner compartment 0. in upwardly ali ned.

relation to'the beaker-tray 23. is a lamp .0! burner B comprising an-outer cy indr cal shell 30 provided in its lower end with a transverse c osure plug 3| peripherally welded or brazed thereto to form a gas-tight permanent seal and being. provided upon its under face with a concentric collar 3| Peripherallv brazed or otherwise secured within and across the upper end of the-shell 3.0 b

is a burner-plate 32. inte rally provided unon its under face with a depending cylind ical skirt .33 threadedly en aged. around its lower peripheral margin. as at 34. with the inner fa e of the shell 3|. plementarily under-cut, as at 35, 36, respectively, to provide a chamber 31 wh ch communicates throu h the walls of the shell 3| with a water Both the shell 3| and the skirt 33 are cominlet pipe 38 and a water outlet pipe 39-'in'the provision of a water jacket for cooling the lamp or burner B. Extending axially through the shell 30 and being brazed at its ends to the p1ug3| and burner plate 32 is a steel tube 4| in the formation of a as chamberfl within the shell 30; The

burner plate 32 is provided ust'inwardlyof the skirt 33 with a uniformly spaced annular series of ap rtures orburner-ports 40 opening into the gas chamber 0.

Ri idly moun ed and ti htly sealed within the upper end of the tube 4| is an inserted nozzle 42 having a downwardly d pressed conical upper face 43 and a central or, axial bore 44 which flares out at its lower end as at 44'.

The nozzle 42 is turned down along its lower or interior end .in

the provision of anexternallv threaded neckportion 45 for en agement with the upper jend: of a nozzle-tube 46 which extends snugly through the steel tube 4| being releasably .locked in place by aset screw 41 threadedly mounted in and extending radially through the collar 3 ed or otherwise tightly, secured within the lower end of the nozzle tube 46 is a gland sleeve 48 internally bored as at 49 and counterbored as at 50 for receiving a packingring 5| held in place by an axially bored packing screw 52. Similarly Weldthe nozzle 42 so as to provide an annular space between the nozzle-bore 44 and the liquid tube or capillary 56 and thereby create'a Venturieffect at the mouth of the nozzle .42, It should bev noted in this connection that the upper. end

of the capillary 56 should preferably be precisely concentric with the bore 44 to insure maxirnum uniformity and accuracy of analytical results. The capillary 56, furthermore, may be adjusted vertically up or down so that its upper or discharge end will be lo'catedat an optimum position in relation to the upper-or discharge 'end of the bore 44, since it has been found that this adjustment is somewhat critical for the different groups of unknown chemical elements, as to which the analytical determination is being made.- For example, if the solutionis to be analyzed for sodium content the adjustment'can be made. empirically using known standard solutions and then left at that setting for subsequent sodium determinations on unknown solutions. It is, of course, obvious that such adjustment can be made at the time the -instrument is being built initially and fixed permanently as by soldering or welding, in which case the instrument .isthereafter permanently a sodium analysis device, or the adjustment can be left unfixed so that the user may make appropriate adjustments from time to time as necessity requires, in which case the instrumentismore or less universal in its applicability.

- Brazed into and extending through the nozzle tube 46 is a tubular lateral off-take 51 for connection to an oxygen line 58 (see Figure 1) and 'threadedly mounted .in the shell 3| is an elbow '59 having an integral vertical leg which is in turn integrally provided with a Venturi-type T connection 6| having a as -ofl-take B2 and an oxygen off-take 63 forconnection respectively througha hydrogen or gas supply line 64 and oxygen line to sources of hydrogen or other suitable inflammable gas and oxygen (not shown). As the high pressure. oxygen rushes through the off-take 63 past the orifice of the off-take 62. suction. is-exerted on the hydrogen line 54 which draws hydrogen or other suitable inflammable gas into the oxygen stream.

Supported withinthe chamber 0 for upward and downward shifting movement in vertically aligned relation to the burner B, by means of a welded in the upper end of the nozzle'tube 46, in

downwardly spaced relation to the nozzle 42, is a collar 53 having an annular. series of apertures 54 and a central-bore 55 axially aligned with the bores of the gland-sleeve 4 8 and the packing.

screw 52 for supporting a fine-bore liquid-tube or capillary 56 which extends axially. therethrough and projects downwardly at its lower end for a substantial distance below the packing screw 52 so as todipdown into the liquid sample held within the beaker 24 when the. tray bar 2| is in elevated position. It should be noted; in

.. this connection thatthe'lo'wer or intake end of --line 64 and the gas which fills the chamber 9 exits through the burner ports 40. The burner Bmay then be lit by lifting the chimney 61 and applying a match or other conventional pyrophoric means to the stream of gas issuing from the burner-posts 4|I. The oxygen is then turned on to the line 65 and the gas pressures in the lines 64, 65, are adjusted by conventional pressure regulators (not shown) until the gases burn steadily and evenly in a light blue practically colorless flame. Under these conditions the flame will burn straight up, so to speak, in the form of a vertical cylinder.

The oxygen is then turned on to the oxygen supply line 58 and pressure carefully regulated by a conventional regulating valve.(not shown). This stream of oxygen will flow upwardly through the nozzle tube 46 and issue in a highpressure blast through the constricted orifice formed between the nozzle-bore 44 and the upper end of the capillary 56 causing the flame to taper down to an intensely hot conical blast and also creating a Venturi-effect directly upon the capillary 56. Thereupon, a suitable quantity of the liquid sample is placed in a carefully cleaned beaker 24 and the latter set into the tray 23. Thereupon the tray-bar 2| is pulled upwardly and forwardly elevating the beaker 24 so that the intake end of the capillary 56 will dip down into the liquid. By rotating the shaft 25 and turning the locking blade 21 into upright position the tray-bar 2| is held in elevated position as shown in Figure 2. The suction capillary 56 draws the liquid sample upwardly in a constant flow. As the liquid leaves the upper end of the capillary 56 it is immediately atomized or volatilized and projected into the interior of the flame for immediate ionization. It should be noted that the volatilization and ionization of the solution are practically simultaneous.

As the sample is ionized in the flame, a characteristic color will be imparted thereto, such as yellow for sodium, red for lithium and so on. Furthermore, the degree of intensity of coloration is directly proportional to the percentage of such cation in the sample. This degree of color intensity produces a voltage emission by the photo-cells l2 and the circuit balanced to measure the output voltage emitted responsive to such color intensity. The knobs l0, H, are turned to increase or decrease the balancing voltage until the indicator 8 shOWS a condition of exact circuit balance whereupon the voltage may be read on the galvanometer 9. Where, as is usually the case, the solution contains more than one cation suitable fllters l may be employed to screen out all other wave length of ight other than the one associated with the Jparticular cation for which the analysis is be-,

ing made. If results as to other cations are desired the filters l5 may be changed successively to transmit, and permit analysis for, one characteristic wave length at a time. During analytical procedure the pressures of entering gases must be held constant within very close limits. A minute amount of a non-ionic wetting agent, such as polyalkylene ether of a partial lauric acid, should preferably be added to the sample to facilitate passage up the capillary 56. It has been found that such substances when added to all samples in precisely the same amount do not adversely effect the results of the herein described spectro-pbotometric method for quantitative analysis but aid in the maintenance of even flow of the sample upwardly through the liquid tube or capillary 56 at a uniform rate.

With apparatus of the present invention variations in ambient temperatures and atmospheric conditions have no adverse effect upon the analytical results. The burner of the present invention furthermore obviates all side-efiect due to condensation of volatilized liquid, inasmuch as a constant amount of liquid per unit of time is delivered directly into the flame.

It should be understood that changes and modifications both in the methods as well as in the form, construction, arrangement, and combination of the several parts of the apparatus for spectra-photometric quantitative analysi may be made and substituted for those herein shown and described without departing from the nature and principle of the present invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A method of spectra-photometric analysis of liquid which comprises generating a substantially colorless intensely hot flame, and injecting the liquid to be analyzed directly into the interior portion of the flame and at the base thereof in a high-pressure blast of oxygen to impart color thereto, imposing the light from the colored flame upon an electronic device capable of emittin a measurable electric impulse directly proportional to the light stimulus and measuring said electric impulse.

2. A method of spectra-photometric analysis of liquid which comprises generating a substantially colorless intensely hot flame, and injecting the liquid to be analyzed directly into the interior portion of the flame and at the base thereof in a high pressure blast of oxygen and atomizing the liquid at the point of introduction into the flame to impart color thereto, imposing the light from the colored flame upon an electronic device capable of emitting a measurable electric impulse directly proportional to the light stimulus and measuring said electric impulse.

3. In a spectro-photom'etric analytical apparatus, a flame generating burner comprising a chamber for receiving a combustible mixture of gases, said chamber bein provided with a plurality of spaced burner-ports adapted to produce a hollow flame, injector means extending through said chamber and having a discharge nozzle opening into the interior portion of the hollow flame, said injector means being provided with a connection for receiving a high-pressure combustion-supporting gas, and a liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the burner for insertion into a body of liquid to be analyzed.

4. In a spectre-photometric analytical apparatus, a flame generating burner comprising a water-jacketed chamber for receiving a combustible mixture of gases, said chamber being provided with a plurality of spaced burnerports adapted to produce a hollow flame, Venturi-type injector means extending through said chamber and having a discharge nozzle opening into the interior portion of the hollow flame, said injector means'being provided with a connection for receiving a high-pressure combustion-supporting gas, and a liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the burner for insertion into a body of liquid to be analyzed.

5. In a spectro-photometric analytical apparatus, a flame generating burner comprising a chamber for receiving a combustible mixture-of ases, said chamber being provided with a plurality of spaced burner-ports adapted to produce a hollow flame, injector means extending through said chamber and having a discharge nozzle 7 Opening into the interior portion of the hollow flame, said injector means being provided with a connection for receiving a high-pressure combustion-supporting gas, and a vertical liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the burner for insertion into a body of 11:- uid to be analyzed.

6. In a spectro-photometric analytical apparatus, a flame generating burner comprising a chamber for receiving a combustible mixture of gases, said chamber bein provided with a plurality of spaced burner-ports adapted to produce a hollow flame, injector means extending through said chamber and having a discharge nozzle opening into the interior portion of the hollow flame, said injector means being provided with a connection for receiving a high-pressure combustio n-supporting gas, and a straight liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the burner for insertion into a body of liquid to be analyzed.

'7. In a spectro-photometric analytical apparatus, a flame generating burner comprising a chamber for receivin a combustible mixture of.

gases, said chamber being provided with a plurality of spaced burner-ports adapted to produce a hollow flame, injector means extending through said chamber and having a discharge nozzle opening into the interior portion of the hollow flame, said injector means being provided with a connection for receiving a high-pressure combustion-supporting gas, a straight liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the lower end of the burner for insertion into a body of liquid to be analyzed, and elevator means located in downwardly spaced relation to the intake tube for shifting a sample-container toward and away from the intake tube.

8. In a spectra-photometric analytical apparatus, a flame generating burner comprising a chamber for receiving a combustible mixture of gases, said chamber bein provided with a plurality of spaced burner-ports adapted to produce a hollow flame, injector means extending through said chamber and having a discharge nozzle opening into the interior portion of the hollow flame, said injector means being provided with a connection for receiving a high-pressure combustion-supporting gas, a straight liquid intake tube disposed within and extending coaxially through the injector means, said tube terminating at one end adjacent to the discharge nozzle and at its other end projecting outwardly from the lower end of the burner for insertion into a body of liquid to be analyzed, elevator means located in downwardly spaced relation to the intaketube for shifting a sample-container toward and away from the intake tube, and locking means for optional engagement with the elevator means to hold the latter in position wherein the intake tube dips into the liquid to be analyzed as it is held in the sample-container.

9. In a spectra-photometric analytical apparatus, a flame generating burner comprising a shell having opposite end walls providing a cylindrical chamber, one of said end walls being end projecting outwardly from the burner for insertion into a body of liquid to be analyzed, and oxygen intake means provided at the lower ends of said nozzle tube, whereby upon discharge through the nozzle the oxygen will cause the hollow flame to taper downwardly to form a conical blast. i

10. In a spectre-photometric analytical apparatus, a flame generating burner comprising a cylindrical chamber for receiving a combustible mixture of gases, said chamber 'being provided in its upper end face adjacent its periphery with a plurality of annularly spaced burner-ports adapted to produce a hollow flame upon combustion of the gaseous mixture, a nozzle tube extending through said chamber in concentricity therewith and having a discharge nozzle opening into the interior portion of the hollow flame, said discharge nozzle havin a downwardly depressed conical upper face and a central bore which flares outwardly at its lower end, said nozzle tube being provided with a liquid intake tube in axial alignment therewith which projects at its lower end outwardly from the burner for insertion into a body of liquid to be analyzed, said liquid intake tube bein disposed at its upper end within the bore of the discharge nozzle spacedly from the walls of said bore, and a source of oxygen under pressure, said nozzle tube being provided at its lower end with intake means from said source of oxygen, whereby upon upward flow of the oxygen through the nozzle tube an area of decreased pressure will be developed adjacent the upper end of the liquid intake tube by flow oi the oxygen through the discharge nozzle causing the liquid to be ejected upwardly into the flame, said hollow flame tapering downwardly by discharge of the oxygen to form an intensely hot conical blast for volatilization and ionization of the ejected liquid.

11. In a spectro-photometric analytical apparatus, a flame generating burner comprising a cylindrical chamber for receivin a combustible mixture of gases, said chamber being provided in its upper face adjacent its periphery with a plurality of spaced burner-ports in concentricity with said chamber and adapted to produce a hollow flame, a nozzle tube extending through said chamber in axial alignment therewith and hav-- ing a discharge nozzle opening into the interior portion of the hollow flame, said discharge nozzle having a downwardly depressed conical upper face and a central bore which flares outwardly at its lower end, said nozzle tube being provided with a liquid intake tube in concentricity therewith the upper end of which is disposed within the bore of the discharge nozzle in spaced relation to the walls thereof. the lower end of said liquid intake tube projecting outwardly from the burner for insertion into a body of liquid to be analyzed, elevator means for shifting a sample container toward and away from the intake tube, locking means for optional engagement with the elevator means to hold the latter in position wherein the intake tube dips into the liquid to be analyzed as it is held in the sample container,

a source of oxygen under high pressure, said nozzle tube being provided at its lower end with intake means connected to said source of oxygen, whereby upon upward flow of the oxygen through said nozzle tube and through said discharge nozzle an area of decreased pressure will be caused adjacent the upper end of the liquid intake tube for ejection of liquid into the flame for volatilization and ionization therein, said hollow flame tapering downwardly by attraction to the discharged oxygen to form a hot conical blast.

THEODORE E. WEICHSELBAUM.

REFERENCES crrEr The following references are of record in the file 01 this patent:

UNITED STATES PATENTS Number Name Date 774,447 Muth NOV. 8 1904 1,304,402 Spire May 25, 1919 OTHER REFERENCES Sawyer: Experimental Spectroscopy, page 21, pub]. by Prentice-Hall Inc., New York, 1946.

Cholak et al.: Industrial and Engineering Chemistry Analytical Edition, vol. 16, Dec. 1944, pages 728-734. I

Lundegardh-Zeitschrift fur Physik, vol. 66, 1930, pages 109-114. 7

Bay et al.: Zeitschrift fur Physik, vol. 45, 1927, pages 338, 3 39. 

